Deterrence - Mutual assured destruction (mad)

Paradoxically, however, one interpretation of the missile crisis held that
the decisive factor in its resolution had been America's nuclear
superiority—that if the American nuclear arsenal had not been more
powerful than the Soviet arsenal, the crisis might have turned out
differently. Both sides subscribed to this interpretation at least in
part, which led to a new round in the arms race just as both sides were
moving closer to agreements on nuclear testing. During the mid-and late
1960s, the Soviet Union expanded its military expenditures so that by the
end of the decade, Soviet Strategic Rocket Forces had a new generation of
even more powerful ICBMs at their disposal. At the same time, the
administration of President Lyndon B. Johnson abandoned the idea of
seeking an overwhelming nuclear superiority and settled upon a new measure
of nuclear striking power called "sufficiency." As defined
by the administration it meant having the ability to survive a Soviet
first strike with enough forces intact to retaliate with a devastating
second strike. To do so, the emphasis would be placed on a better balanced
triad structure of U.S. nuclear forces, consisting of missile, air, and
naval strategic forces, together leading to the power to "assure
destruction" to an adversary without engaging in a destabilizing
arms race. Secretary of Defense Robert S. McNamara argued that such a
structure was both cost effective and stable, and it was retained as the
structure of the U.S. nuclear force until the end of the Cold War.

By the beginning of the 1970s, the nuclear forces of the Soviet Union and
the United States were at relative parity. In terms of sheer explosive
power the USSR had surpassed the United States and was in the process of
developing weapons with even larger payloads and greater accuracy, but the
United States retained the technological lead. With this parity came new
challenges to deterrence theory. No longer did one side have a
preponderance of strategic power, and it appeared doubtful that even a
preemptive first strike would hold the advantage, since it was
increasingly clear that neither side would survive a nuclear exchange
without casualties measured in the millions. American policymakers quickly
found, however, that the promise of mutual destruction in the bipolar
contest with the Soviet Union was frustratingly ineffective in conflicts
such as Vietnam, which fell outside of the strictly defined
U.S.–USSR relationship.

Mutual assured destruction (MAD) lay at the heart of the Strategic Arms
Limitation Talks (SALT) that began in Helsinki, Finland, in November 1969.
The objective of the talks was not to reduce the arsenals of either side
but rather to negotiate limits on future growth of those arsenals
precisely to preserve mutual vulnerability. Two technological developments
of the late 1960s threatened to destabilize the nuclear status quo:
antiballistic missile (ABM) systems and the development of multiple,
independently targetable, reentry vehicles (MIRVs) technology. ABM
systems, as they were conceived at the time, were designed to protect
cities from incoming missiles. Both the United States and the Soviet Union
had developed first-generation ABM systems that could in theory, if not
yet in practice, offer protection against first strikes. Partly to
overcome such an advantage, both sides had invested considerable resources
in developing the technology of MIRVs, a system whereby one missile could
deliver several warheads to independent targets. Although these new
technologies were designed to cancel each other out, in truth they
threatened to destabilize the mutual destruction deterrent and spark off a
new arms race, a race that would not only be dangerous, but expensive. The
SALT process, therefore, was designed to limit these technologies and keep
each side vulnerable to attack by the other.

With strategic nuclear war finally recognized as unwinnable, President
Richard M. Nixon ordered Secretary of Defense James Schlesinger to review
the military posture of the United States in light of recent technology.
The result, known as the Schlesinger Doctrine, was essentially a
refinement of flexible response, designed to balance Soviet bloc
capabilities by threatening retaliation commensurate with the threat.
Specifically, it enhanced the role of tactical nuclear weapons in a
three-layered defense structure: conventional forces for conventional
threats; tactical nuclear forces to counter tactical nuclear threats; and
strategic nuclear forces to counter strategic threats. In essence, the
Schlesinger Doctrine embraced what Henry Kissinger had proposed in the
late 1950s: that a limited nuclear war was possible and was a desirable
capability to have.

Despite President Jimmy Carter's efforts to further détente
and continue the focus on nuclear sufficiency rather than superiority, the
international and domestic political environments of the late 1970s
actually pressured the administration to increase military spending
drastically. During the presidential election campaign of 1980, the
Republican candidate Ronald Reagan seized upon accusations made by
prominent groups such as the Committee on the Present Danger, headed by
Eugene Rostow and Paul Nitze, to accuse the Carter administration of
allowing a window of vulnerability to open, claiming that détente
had allowed the Soviets to gain a dangerous lead in the arms race to the
point that even the hardened-silo Minuteman forces, the mainstay of the
U.S. strategic missile force, were vulnerable to high-yield Soviet
missiles. Reagan promised not only to neutralize that gap, but also to
restore American military superiority and, to that end, deliberately
strove to upset the balance of terror by focusing on defense rather than
deterrence. The shift had important ramifications for the Cold War. Reagan
reauthorized the development of the B-1 bomber and the next generation of
highly accurate and MIRV-equipped Peacekeeper missiles to replace the
aging Minuteman forces. He also authorized development of a controversial
radiationenhanced weapon, the neutron bomb, which killed living matter but
left nonliving matter relatively unscathed. At the same time, Reagan
endorsed the recommendations of a high-level commission chaired by Brent
Scowcroft calling for an evolution toward small, single-warhead ICBMs
backed up by Peacekeeper missiles.

In 1983 President Reagan ordered a large-scale scientific and military
project to examine the feasibility of a new generation of ABM defenses.
Officially labeled the Strategic Defense Initiative (SDI), but more
commonly known as Star Wars after the popular science-fiction movie, the
objective was to develop a multilayered shield capable of stopping
thousands of incoming ballistic missiles. In theory, lasers mounted on
satellites, electromagnetic guns, and charged particle beam weapons would
be used to shoot down incoming ballistic missiles anywhere from boost
phase (soon after launch) to reentry (final descent to target). In
championing the project, Edward Teller, the reputed "father of the
H-bomb," made a dramatic and controversial return to the public
debate of deterrence. Not only was the technology unproven, but it quickly
became apparent that the price tag of such a system was almost impossible
to predict and entirely impossible to pay. Not surprisingly, the Soviet
Union reacted angrily to what seemed a blatant disavowal of the 1972 SALT
Treaty. Nevertheless, Reagan ordered the project to proceed. For the
remainder of the 1980s, the Reagan administration struggled to find a way
to make SDI a reality while at the same time continuing to pursue
meaningful arms reduction.